with s as
(select 'Vladimir'   name from dual union all
 select 'Sergey'     name from dual union all
 select 'Iror'      name from dual union all
 select 'Elena'      name from dual union all
 select 'Evgenyi'    name from dual union all
 select 'Konstantin' name from dual union all
 select 'Dmitryi'    name from dual union all
 select 'Maksim'     name from dual
)
select  *
  from  s
  match_recognize(
                  measures
                    match_number() as rn,
                    first(name) as n1,
                    case count(*) when 2 then last(name) end as n2
                    pattern(two*)
                    define two as count(*) <= 2
                 )
  order by rn
/

        RN N1         N2
---------- ---------- ----------
         1 Vladimir   Sergey
         2 Iror       Elena
         3 Evgenyi    Konstantin
         4 Dmitryi    Maksim

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